4/9÷[5/6-(1/6+1/3)]
=4/9÷[5/6- 3/6]
=4/9×3
=4/3
1/15*(1/3+1/12)
=1/15*5/12
=1/36
1/4÷(3-5/13-8/13)
=1/4÷(3-1)
=1/8
望采纳。谢谢
1、4/9÷[5/6-(1/6+1/3)]=4/9÷[5/6-1/6-1/3)]=4/9÷[2/3-1/3]=4/9÷1/3=4/3
2、1/15*(1/3+1/12)=1/15*(4/12+1/12)=1/15*5/12=1/36
3、1/4÷(3-5/13-8/13)=1/4÷[3-(5/13+8/13)]=1/4÷[3-1]=1/4÷2=1/8